1. Field of the Invention
The present invention generally relates to a method for low temperature liquid-phase deposition for forming a low-temperature grown film or a film with excellent step-coverage as a passivation layer on the surface of a semiconductor device having independent circuit functions, and to a method for cleaning a liquid-phase deposition apparatus, in which a loop used exclusively for cleaning is employed so as to prevent SiO2 powders from remaining in the loop.
2. Description of the Prior Art
In recent years, low temperature deposition has become one of the most important techniques for semiconductor device manufacturing in order to avoid degradation of the device characteristics due to the thermal stress on the thin films.
For the most important insulator material used in IC technology, silicon oxide, different deposition conditions results in different characteristics and applications of the thin film. In early days, silicon oxide was grown in the furnace in the temperature range from 700 to 1000xc2x0 C. However, such a temperature range may cause mal-functions of the semiconductor device formed on the substrate because the ohmic contacts degrade due to alloy sintering. On the other hand, for a compound semiconductor device having an active layer formed of III-V semiconductor materials, the V-group components of III-V materials (for example, As in GaAs) may dissolve due to high temperature processing, leading to unreliable material characteristics as well as device failures.
With the improvement in fabrication techniques, a novel silicon oxide growing method known as plasma-enhanced chemical vapor phase deposition (PECVD) has been developed and successfully demonstrated in the temperature range from 300 to 400xc2x0 C. However, it is notable that such a temperature range for silicon oxide growth by using plasma is still too high for deep sub-micron fabrication process, which may lead to device damage during PECVD operation.
Accordingly, various new deposition techniques have been developed. Particularly, low-temperature liquid-phase deposition has attracted considerable attention for its advantages such as low cost and high throughput. In the prior art, a wet trough for low-temperature deposition has a serious problem in that the contaminative particles generated in the wet trough make the control difficult for temperature, on-line monitoring system, solution supply, and cleaning, which may cause trouble in on-line mass production techniques. On the other hand, the prior art has another problem in that the deposition apparatus suffers from poor reliability resulted from the jam in the loop.
Accordingly, there is need in providing a method for low temperature liquid-phase deposition for forming a low-temperature grown film or a film with excellent step-coverage used as a passivation layer on a semiconductor device or as an insulating layer between interconnection metal layers for ICs. The present further provides a method for cleaning a liquid-phase deposition apparatus.
In view of the aforementioned issue, it is the primary object of the present invention to provide a method for low temperature liquid-phase deposition for forming a low-temperature grown film or a film with excellent step-coverage used as a passivation layer on a semiconductor device having independent circuit functions or as an insulating layer between interconnection metal layers for ICs.
It is another object of the present invention to provide a method for cleaning a liquid-phase deposition apparatus, in which real-time monitor of the pH value variation is employed with auto-titration such that the reaction rate is stably controlled in surface reaction region instead of mass transfer process to effectively overcome self-contamination.
In order to achieve the above objects, the present invention provides a method for low temperature liquid-phase deposition, comprising steps of: adding a solute to an H2SiF6 solution, making the solution a saturated H2SiF6 solution; preparing a sample on which a thin film is to be deposited, wherein at least a semiconductor device having independent circuit functions has been fabricated on a surface of the sample; and adding a reactant to the saturated H2SiF6 solution, making the saturated H2SiF6 solution an over-saturated H2SiF6 solution so as to form a thin film by liquid-phase deposition on the sample.
The present invention further provides a method for cleaning a liquid-phase deposition apparatus characterized in that a loop used exclusively for cleaning is employed so as to prevent SiO2 powders from remaining in the loop, comprising steps of, periodically cleaning the apparatus as well as the loop by using a solution added with SiO2; repeating placing the solution and bi-directional circulation; and exhausting the solution into a storage trough for recycling purposes.
Other and further features, advantages and benefits of the invention will become apparent in the following description taken in conjunction with the following drawings. It is to be understood that the foregoing general description and following detailed description are exemplary and explanatory but are not to be restrictive of the invention. The accompanying drawings are incorporated in and constitute a part of this application and, together with the description, serve to explain the principles of the invention in general terms.